Process for manufacturing ortho-amino-aryl mercaptanes and products produced thereby



Patented Jan. 6, 1931 UNITED STATES PATENT- OFFICE ON- THE-IAIN/FEGHENHEIM, GERMANY, INC., 01: NEW YORK, N. Y., A CORPORATI PROCESS FOR MANUFACTURING- ORT HO-AMINO-ARYL MERCAPTANES PRODUCEI.S

ASSIGNORS 1'0 GENERAL ANILINE WORKS,

ON or DELAWARE PRODUCED THEREBY No Drawing. Application filed July 6, 1928, Serial No. 290,881, and in Germany July 9, 1927.

Our present invention has for itssubject a new, useful and very. widely applicable process for the manufacture of ortho-aminoaryl mercaptanes. This process consists in treating at an elevated temperature an arylthiazollc compound of the general formula:

(or its tautomeric form (1) I wherein aryl means a substituted residue of the benzene series, or a IGSldllQOf-tllfl naphthalene or anthracene series, substituted or not substituted, with a concentrated caustic alkali solution with or without the addition of an organic diluent, particularly of an alcohol, whereby the thiazol ring is split off and ortho-amino-arylmercaptanes of the formula: a

NH: 1 sH 2 'thiazol ring only by subjecting the thiazolic compound to the caustic alkali fusion, a

method which is not suitable for producing substituted amino-arylmercaptanes as undesired by-products are formed diminishing essentially the yield of pure products.

The present process is particularly applicable when starting from 2-aminoth1azol compounds, in which the paraposition to the azole nitrogen atom is either substituted by a monovalent radicle or blockaded, which are easily obtainable by acting in an acidic medium with an inorganic sulfocyanide in the presence of a halogen 0n the corresponding primary'aryl-amines according to U. S. application of Kaufmann and Schubert, Serial 50.1%. 183,228, filed April 12, 1927.

The ortho-aminoarylmercaptanes obtained according to our new process have all characteristic properties of this important class metals difiicultly soluble mercaptides and yield in a smooth reaction the corresponding ortho-aminoarylthioglycolic acids when condensed with monochloroacetm acid. Advantageously one may directly use for this latter condensation the alkaline solutions of the mercapto-com'pounds obtained according to our process without isolating the mercaptanes themselves.

In order to further illustrate our invention the following examples are given, the

parts being by weight and all temperatures but it is understood,

in centigrade degrees, that our invention is not limited to the partlcular products or reacting conditions mentioned therein.

Example 1 '5 parts of 2-amino-l-methyl-6-chlorobenzothiazol of the probable formula =NH 01 s/ amino-5-chloro-benzene-3-mercaptane of the formula CH1 k separates and may be isolated in the usual manner. When condensing the solution of the potassium mercaptide in' the usual man ner with the correspondin quantity of the sired to isolate the mercaptane compound,

sodium salt of the monoc oracetic acid, the 1 methyl 2 amino-5-chlorobenzene-3-thioglycolic acid is obtained in a pure state with an excellent yield, it may be isolated in the 5 form of its inner anhydride meltin at 186 and corresponding probably to the ormula:

c s-cn ,co

Example 2 -5 parts of 2-amino-6-ethoxybenzothiazol of the probable formula:

E-NH, 2o oimo s obtainable, for instance,,by acting with bromine on a mixture of para-phenetidine and sodium sulfocyanidein an acetic acid solution are boiled for about 7 hours with 100 arts of a caustic soda solution of about 50 in a vessel provided with a reflux condenser. After cooling down the sodium salt of l-amino-4-ethoxybenzene-2-mercaptane of o the formula:

' cimo H separates and may be isolated in the usual manner. When condensing the solution of the mercaptide with the calculated quantity of monochloracetic acid(sodium salt)the corresponding 1-amino-4-ethoxybenzene-2-thio- 40 glycolic acid is obtained in an excellent yield,

which likewise may be isolated in form of its inner anhydride.

Example 3 12 arts of 2-amino4.5-benzo-6 ethoxybenzot iazol of the probable formula:

E-NH: can s the double quantity of water and if it is destance, by the action of bromine on 4-ethoxythe mass is poured into an acetic acid solution of zinc chloride, whereby the 4-amino-1- ethoxy-3-thionaphthol formed of the formula:

precipitates as zinc salt. It is a new comp ound not hitherto described in literature.

or the production of the corresponding thioglycolic acid the aforesaid diluted reaction mass, containing the sodium saltof the new mercaptane, is directly condensed at about 40-50 with the corresponding quantity of the sodium salt of mono-chloroacetic acid.

(which is likewise a new compound) is thus obtained as sodium salt se arating out in form of colorless leaflets cooled reaction solution. By acidifying the v aqueous solution of the sodium saltthe anhydride of the new thioglycolic acid is obtainedcrystallizing from spirit as colorlessneedles of 227228 melting point.

When starting from 2-amino-4.5-benzo-6- methoxy-benzothiazol of 225 melting point in the same manner the corresponding 4-amino-l-methoxy 3 4 thionaphthol is formed yielding likewise by condensation with monochloracetic acid (sodium salt) the 4-amino-1- methoxy-3-naphthy1-thioglycolic acid, the inner anhydride of which is obtained as colorless needles, melting at 226227, when recrystallized for instance from alcohol.

In the same manner the 2-amino-alphabeta-anthracylthiazole obtainable, for instance, by the action of bromine on beta-anthramine and potassium sulfocyanide in anacidic medium yields the corresponding 2- aminoanthracene-1-mercaptane.

We claim:

1. A process which comprises treating at a temperature exceedin 100 a 2-amino-arylthiazolic compound 0 the general formula:

N\ 4 r-fl'y NHa. wherein aryl means a substituted residue of the benzene series or a residue ofthe naphthalene or anthracene series substituted or not and wherein 3 means that in the benzene nucleus adjacent to the thiazol-ring the 4-position to the azole nitrogen atom is either subom the stituted or blockaded with a concentrated caustic alkali solution. 2. A process which comprises treating at about 120-160 a 2-amino-arylthiazolic compound of the general formula:

wherein aryl means a substituted residue of the benzene series or a residue of the naph- 10 thalene or anthracene series substituted or not and wherein 3 means that in the benzene nucleus adjacent to the thiazol-ring the 4-position to the azole nitrogen atom is either substituted or blockaded, with a concentrated caustic alkali solution.

3. As new compounds o-aminomercaptanes of the general formula:

25 forming insoluble heavy metal salts and yielding the corresponding new ortho-amino-thioglycolic acids by condensation with monochloroacetic acid.

4. As a new compound the l-ethoxyi-am- 30 ino-3-thionaphthol of the formula:

forming insoluble heavy metal salts and yielding when condensed with monochloracetic acid the new 1-ethoxy-4-aminonaphthalene-3-thioglycolic acid, the anhydride of which melts at 227-228. in a pure state.

In testimony whereof, we aflix our signa- 

